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June 4, 1963
c. R. MURPHY
PROCESS FOR THE RECOVERY OF METHANOL
Filed Oct. 9, 1959
3,092,667
United States Patent O
CC
3,092,567
Patented .lune 4, 1963
1
2
3,092,667
gauge by any suitable means, for example by passage
through heat exchanger 16 in indirect relationship with
recycle hydrocarbon gas passing therethrough from line
PROCESS FOR THE RECOVERY 0F METHANOL
Clarence R. Murphy, Allison Park, Pa., assigner to Gulf
Research & Development Company, Pittsburgh, Pa., a
corporation of Delaware
18 on its way to line 4.
From heat exchanger 16 the partial oxidation product,
including unoxidized gaseous hydrocarbon, is passed by
'
Filed Oct. 9, 1959, Ser. No. 845,459
2 Claims. (Cl. 260-632)
line 20 to extractor 22 which is maintained at a tem
perature of about 120° to about 220° F. and a pressure
of about 100 to about 150 pounds per square inch gauge.
This invention relates to a process for obtaining meth
anol and more particularly to a process for recovering 10 Water is _introduced therein by line 24. Water contain
methanol obtained as a result of the partial oxidation
ing the absorbed formaldehyde is removed from the base
of normally gaseous hydrocarbons Vsuch -as propane.
of extractor 22 by line 26 and passed to suitable re
The partial oxidation of normally gaseous hydrocar
covery means to obtain the desired formaldehyde. The
bons results in an oxygenated mixture comprising formal
remainder of the product is removed overhead from ex
dehyde, acetaldehyde, methanol, higher alcohols such as
tractor 22 by line 28 and passed .to extractor 30 which
ethanol, propanol, butanol, etc., acetone, acetals and
is maintained at a temperature of about 85° to about
ethylene and propylene oxides. Formaldehyde and sub
120° F. and a pressure of about 100 to about 150 pounds
sequently acetaldehyde can be removed from the oxy
per square inch gauge. Recycled water containing some
genated mixture. Methanol can then be recovered from
absorbed formaldehyde is introduced into extractor 30
the remainder of -the oxygenated mixture. Recovery of
pure methanol from said remainder is complicated, how- _
ever, since many of the impurities which are also pro
by line 32, a portion of which forms the supply for line
24, and fresh make-up water by line 34. Unreacted
gaseous hydrocarbon is removed overhead from extractor
30 by line 36 and can be recycled directly, or after any
naturally admixed therewith, for example, dimethyl ace
suitable treatment, to line 18.
tal, acetone, higher acetals, etc., boil very close to meth 25 -The product removed ‘from the base of extractor 30
anol or form azeotropes therewith.
is passed by line 38 rto tower 40 which can be maintained
I have found that the recovery of pure methanol from
ata top temperature of about 150° to Iabout 250° F. and
an oxidation mixture such as that described above can
a pressure of about 0 ft-o tabout 30 pounds per square inch
be facilitated by a process which comprises separating
gauge. Water containing some absorbed formaldehyde
formaldehyde and acetaldehyde from an oxygenated mix 30 is
removed from the base of tower 40 by line 32 and
duced in the partial oxidation reaction and which are
ture obtained as a result of the partial oxidation of nor
mally gaseous hydrocarbons, subjecting the remaining
recycled by the designated lines to extractors 22 and 30.
and carbonyl-containing compounds, said mixture having
also introduced into line 42. The resulting mixture, pref
The total product remaining, including iacetaldehyde,
mixture to hydrogenation conditions to obtain a hydro
methanol,
ethylene Aand propylene oxides, methyl formate,
genated mixture containing no more than about 5, prefer
ably containing no more than about 3 percent by weight 35 methylal, acetone, dimethyl lacet-all, etc., is removed from
tower 40 Iby 'line l42. If desired, any methanol which
of carbonyl-containing compounds, separating from said
may be present in line 26 can be separated therefrom and
hydrogenated mixture a mixture comprising methanol
a boiling point below about 160° -to about 170° F., ex
tracting said latter mixture containing methanol and
said latter carbonyl-containing compounds with water,
and thereafter recovering methanol from said extract.
The present invention can further be illustrated by
reference to the accompanying ilow diagram which is
hereby incorporated-in the present speciñcation.
erably 'auter treatment with «an ion yexchange resin for the
40 f_pu-rpose of Vconverting said oleiin oxides to the corre
sponding glycols, is passed to fractionation tower 44
which is maintained at a top temperature of about 125°
to about 1|35° F. «and a pressure of labout 30 to Iabout 40
pounds per square inch gauge. As ya result thereof puri
45 iied acetaldehyde is removed from tower 44 by line 46.
Referring to the ñow diagram, a normally gaseous
hydrocarbon such as ethane, propane or butane, is intro
duced into the system by line 2, recycled normally gaseous
hydrocarbon by line 4 and oxygen by line 6. The result
ant mixture is generally at a temperature of about 5501"
to about 600° F. and a pressure of about 100 to about
150 pounds per square inch gauge. 'Ihe resultant mix
ture will contain about 70 to about 80 volume percent
of normally gaseous hydrocarbons, about 2 to about 4
volume percent of oxygen, the remainder- being gases 55
inert to the desired oxidation reaction, such as carbon
monoxide, carbon dioxide, etc.
The resultant mixture is charged to preheater 8 where
in said mixture in about 0.1 to about 0.2 second is
raised to -a temperature of about 600° to about 750° F. 60
and a pressure of about 100 to about 150 pounds per
square inch gauge. The heated mixture is removed from
preheater 8 by line 10 and passed to reactor 12 wherein
the mixture is reacted at a temperature of about 700° to
about 900° F. and a pressure of about 100 -to about 150
pounds per square inch gauge for about 0.1 to about 2.0
seconds. The partial oxidation product obtained in oxida
The remainder of the product, issuing «from the base of
tower 44, by line 48, typically, can have the following
composition:
Compound:
Percent by weight
Water _____________________________ __ 5 rto 10
Methanol __________________________ __ 50 to 70
Acetaldehyde »and acetone ____________ __ Ito 10
Ethanol _
_
1 to l5
Isopropanol ________________________ __
n-Propanol _________________________ __
4 to 'l0
lto 5
-Butanols __________________________ __
Miscellaneous iacetals ________________ __
1to 5
lto 5
Zto 7
Dimethyl -acetals ____________________ __
Ethylene and .propylene yglycols ________ __
1 to 10
The product in line 48 is then introduced into hydro
generator `50 which is packed with »a hydrogenation cat
alyst such las nickel, copper, chromia, etc., and maintained
at a temperature of «about 300° to about 350° F. and a
pressure of about 600 to about 1000 pounds per square
inch gauge. The oxygenated product as well «as suilicient
tion reactor 12 is removed therefrom by line 14 and
hydrogen is passed through hydrogenation reactor 5-0 at
within about 0.1 to about 2.0 seconds is cooled toV a
la
space velocity, volume of product per volume of catalyst
70
temperature of about 300° to about 400° F. and a pres
per liour, `of about 0.25 to about 1.5. As `a result of such
sure of about 100 to about 150 pounds per square inch
treatment, a substantial amount of the aldehydes present,
3,092,667
¿i
and acetaldehyde had been removed, had the following
formaldehyde, acetaldehyde, propionaldehyde, `and acro
lein; ketones, acetone and methylethylketone; and acetals,
methylal and acetaldehyde dimethyl `acetal, 'are hydro
genated to the corresponding alcohols. As previously
analysis:
Table I
Compound:
Methanol
noted, it is critical in the practice of the present invention
that the weight percent of carbonyl-containing compounds,
Acetaldehyde
on a water-free basis, in the hydrogenated product be no
more than about 5, preferably no more than about 3
Normal propanol
Acetone
0
_
Isopropanol
percent by weight. A typical hydrogenated product will
Butanol
Ethanol
have the following composition:
Compound:
Percent by weight
_
Dimethylacetal
Percent by weight
p
Miscellaneous acetals _________________ ___--- »
Methanol _________________________ __ 5‘5 to 75
Acetaldehyde and acetone ____________ __ 0 to 0_5
15
Dimethylacetal _____________________ __ 0 to 0.5
This charge, containing 21.8 percent by weight of car
Ethanol _
bonyl-containing compound on a water-free basis, was
__
__
____
Sto
15
Water
passed through a hydrogenation reactor containing a
ísopropanol _______________________ __
n-Propanol ________________________ __
Butanol ___________________________ __
3 to l0
2to 6
1 to 5 20
Miscellaneous acetals ________________ __
lto
‘2
was found to contain 2.9 percent by weight, on a Water
Water
Sto l0
free basis, of carbonyl-containing compounds. The hy
__
_
__
Ethylene and propylene glycol ________ __
1 to 10
From hydrogenator 50 the hydrogenated product is
25
passed «by lline 52 to distillation tower 54 wherein meth
-anol and carbonyl-containing compounds boiling up to
nickel catalyst at a temperature of 350° F., a pressure of
600 pounds per square inch gauge and a liquid hourly
space velocity of about one. The hydrogenated product
drogenated product was charged to a water extractor with
a Weight ratio of water to feed of 2.5 :1 and a top tem
perature of 170° to 200° F. and a pressure of 0 pounds
per square inch gauge. The water contained 1.0 percent
by weight of sodium hydroxide. The bottoms product
about 160° to ‘about 170° F. are separated therefrom.
from the first extractor was sent to a second extractor
operated under the same conditions as the ñrst extractor.
30
distillation tower S4 of `about 160° to labout 170° P_and
In each case, the non-polar contaminants coming off over
This can be done by maintaining -a top temperature in
a pressure `of about 0 to about 5 pounds per square inch
gauge. As `a result of such treatment a mixture contain
ing methanol, acetone, ethanol, etc., is removed from dis
tillation tower 54 by lline 56. The remainder of the
oxygenated product is removed from the base of distilla
head Were recycled to the hydrogenation reactor. „The
bottoms from the second extractor was sent to a 60-plate
distillation column run at 10:1 reiiux ratio, with a top
35 temperature of 148° lF. and a pressure of 0 pounds per
tion tower 54 by line 58 for further treatment as desired.
The product in Iline 56 is passed to extractor 60 wherein
it is subjected to extractive distillation conditions for the
square inch gauge, where the methanol was removed as
an overhead product and the remainder, chiefly higher
alcohols, as a bottoms product. The methanol> was un
' able to pass the standard permanganate test (ASTM Test
purpose of removing therefrom the low-boiling carbonyl
No. D268-53). In addition, there was a 10 percent loss
>containing compounds or other impurities ladmired there 40 of methanol with the water as a bottoms product.
with. This is done by maintaining in extractor 60 »a
Operation in accordance with the present invention is
temperature of about 170° to about 200° F. land a pres
illustra-ted below in Example II.
sure yof about 0' to about 5 pounds per square inch gauge
' EXAMPLE n
while introducing therein by line 62 about one to about 5
percent by weight of water based on the product intro 45 YThe same charge employed in Example I was hydrogen
duced therein by line 56. In order to polymerize alde
ated under the same conditions until V`a hydrogenated
hydes which may be present »and stabilize the acetals
product containing 3.65 percent by weight of carbonyl
which rare present, the water in line 62 can contain about
containing compounds was obtained. This product was
0.1 to ‘about 2.0 percent by weight `of a basic reagent such
sent to a 60-plate distillation column having a top tern
as sodium hydroxide, calcium hydroxide, potassium hy 50 perature of 155 ° F. and a pressure of 0 pounds per square
droxide, etc. As la result thereof, the .oxygenated im
inch gauge. Methanol and light carbonyl-containing im
purities are removed overhead by line 64 and are prefer
|ably recycled to hydrogenator 50. The product which is
purities were removed from the top of the column, and
the remainder, comprising water and higher alcohols were
removed from the base of extractor 60 by ‘line 66 is
removed from the base thereof. The product from the
passed to fractionator 68 which is maintained at a top 55 top of the distillation column was sent to a water extractor
temperature of «about 147° to about 150° F. 'and a pres
with a weight ratio of water to feed of 2.511 wherein the
sure of yabout 0 to about 5 pounds per square inch gauge.
top` temperature was 185° F. and the pressure 0 pounds
Under such conditions methanol having a pur-ity of 99.95
per square inch gauge. The Water contained one percent
percent by weight is removed from fractionator 68 by line
by weight of sodium hydroxide. The low-boiling im
’70. The remainder of the product therein, water, con 60 purities which were removed from theV top ofthe water
taining the basic reagent when used, is removed from the
Vextractor were recycled to the hydrogenation zone, while
base thereof by line 7 2. Y'
Y
the remainder of the product was sent to fractionating
The invention can further be illustrated by reference to
tower containing 60 plates and operated at a top tempera
the following examples. Example I, which was not op
ture of 148° F. and a pressure of 0 pounds per square
erated in accordance with my invention, clearly shows 65 inch gauge with a reflux ratio of'7z1. Methanol free of
the disadvantage of attempting to recover methanol with
carbonyl-containing compounds was obtained as an over
out first separating from the hydrogenated mixture ma
head product. This methanol passed the standard per
terials boiling above about 160° to about Y170° F.
manganate test referred to above with a two hour time.
70 Only 3 percent by weight of methanol was lost with the
EXAMPLE I
bottoms product.
Y
That it is imperative that the amount of carbonyl-con
taining compounds must be within the defined range after
hydrogenation and prior to further treatment is apparent
and from which subtantially all of the formaldehyde 75 from Example IH below.
-In the present example, as well as the following exam
ples, the charge to the hydrogenation reactor, which was
obtained as a result of the partial oxidation of propane
5
3,092,667
d
EXAMPLE III
In this run the procedure employed was identical to
that of Example II except that the product after hydrogen
ation was found to contain 6.45 percent `by weight of
carbonyl-containing compounds. The methanol recov
of about 147° to about 150° F. methanol from said ex
ered failed to pass the standard permanganate test re
oxidizing propane with a gas containing molecular oxygen
at a temperature of about 700° to about 900° F. to obtain
hydroxide, potassium hydroxide and calcium hydroxide
and thereafter recovering by distillation at a temperature
tract.
2. A process for obtaining methanol which comprises
ferred to above. Three percent by Weight of methanol
an oxygenated mixture containing essentially formalde
was lost.
hyde, acetaldehyde, methanol, higher alcohols, acetone,
Obviously, many modifications and variations of the in
vention as hereinabove set forth, can be made without de
acetals and ethylene and propylene oxides, removing
parting from the spirit and scope thereof, and therefore
only such limitations should be imposed as are indicated
in the appended claims.
formaldehyde by extraction with `Water and a portion of
the acetaldehyde by fractionation from the oxygenated
mixture and obtaining an oxygenated product containing
in excess of about tive percent by Weight thereof of car
I claim:
1. A process for obtaining methanol which comprises 15 bonyl-containing compounds consisting of acetaldehyde,
acetone and acetals, directly subjecting said latter oxygen
ated product to hydrogenation With hydrogen in the pres
oxidizing a gas selected from the group consisting of
ethane, propane and butane with a gas containing molec
ular oxygen at a temperature of about 700° to about 900°
F. to obtain an oxygenated mixture containing essentially
ence of a hydrogenation catalyst at a temperature of about
300° to about 350° F. to ‘obtain a hydrogenation product
20 containing from about one to about three percent by
Weight of carbonyl-containing compounds, distilling 4from
acetone, acetals and ethylene and propylene oxides, re
said hydrogenation product at a temperature of about
moving formaldehyde by extraction -With Water and a por
160° to about 170° F. a product consisting essentially of
tion of the acctaldehyde by fractionation from the oxy
methanol and carbonyl-containing compounds, extracting
genated mixture and obtaining an oxygenated product
containing in excess of about ñve percent by Weight there 25 said methanol product with Water containing sodium hy~
droxide and thereafter recovering by distillation at a tern
of of carbonyl-containing compounds consisting of acetal
perature -of about 147° to about 150° F. methanol from
dehyde, acetone and acetals, directly subjecting said latter
said extract.
oxygeuated product to hydrogenation with hydrogen in
formaldehyde, acetaldehyde, methanol, higher alcohols,
the presence of a hydrogenation catalyst at a temperature
of about 300° to about 350° F. to obtain a hydrogenation 30
References Cited in the ñle of this patent
product containing from about one to about three percent
UNITED STATES PATENTS
by weight of carbonyl-containing compounds, distilling
from said hydrogenation product at a temperature of
about 160° to about 170° F. a product consisting essen
tially of methanol and carbonyl-containing compounds,
extracting said methanol product with Water containing a
basic reagent selected from the group consisting of sodium
35
2,115,553
2,151,461
2,470,222
2,569,671
2,868,849
Giesen et al ___________ __ Apr. 26,
Britton et al ___________ __ Mar. 2l,
Patterson _____________ __ May 17,
Hughes et al. __________ -_ Oct. 2,
Leach et al ____________ _.- Jan. 13,
1938
1939
19491951
1959